It's kind of taboo to draw Mohammad or God in Islam. And by "kind of" taboo, I mean pretty damn taboo.

The idea is that it might lead to idolatry, and idolatry is a major no-no in Islam. I was just in India a few weeks ago, and the easiest way to tell a Hindu temple from a mosque in the absence of prior knowledge was to look at the decoration. There were no identifiable images on or in the mosques- it was all abstract and geometrical, because they don't want anything that might potentially be an idol.